It's in the first paragraph so that the reader will read it soon and
understand the purpose of the letter. Click here to see the answer in the letter above.

Order No. 284/HG is the subject heading of the letter, the order number
of the order of teak outdoor furniture, and the
right place to file this letter in Sudano Teak's filing system. 'No.' is an
abbreviation for 'Number'.

'Meeting about Order No. 284/HG' would be a better subject heading because this letter is
mainly about arranging a meeting.

So that the reader knows which order this letter refers to and can
easily find other information about this order, such as the quantity of furniture ordered.

'Your sincerely' is the correct expression to use if you write 'Dear'
and the person's family name; e.g. 'Dear Mr Sarempaet.'